Recently, wireless devices that use the ISM (Industry Science Medical) band around 2.4 GHz band have been come into wide use in an accelerated way. The ISM band overlaps the UNII (Unlicensed National Information Infrastructure) and used for wireless LANs.
The ISM band is used for not only the wireless LANs but also Bluetooth, Zigbee, microwave ovens, cordless phones, and the like.
For that reason, when wireless devices (wireless base station, wireless LAN terminal, and the like) are in the process of wireless communication with each other and a radio wave is generated from a radio wave generator (Bluetooth, Zigbee, a microwave oven, a cordless phone, or the like) that uses at least a radio wave in a frequency band that overlaps the frequency band used by the wireless devices, radio interference occurs between the wireless devices and the radio wave generator. As a result, frames may collide against each other or frame resending may delay the transmission, and the transmission quality may be degraded.
To address the problem, a technical document that has been applied prior to the present invention (for example, see Patent Document 1) discloses a wireless LAN device that performs data communication near a microwave oven by using a radio wave in a frequency band near a microwave for a heating purpose generated from the microwave oven, characterized by including: a microwave oven operation detection device that is incorporated in the microwave oven and includes a detection circuit that detects timing of generation of the microwave and a transmission circuit that transmits a signal representing a detection result of the detection circuit; and a plurality of wireless terminal devices each of which performs data communication by using a radio wave, wherein each of the wireless terminal devices includes: a communication circuit that is capable of being switched between a first data communication scheme for performing wireless communication when the microwave oven does not generate the microwave and a second data communication scheme that is capable of performing communication with little interference of the microwave when the microwave oven generates the microwave; a recognition circuit that receives the signal from the transmission circuit of the microwave oven operation detection device and recognizes the timing of generation of the microwave from the microwave oven according to the detection result of the detection circuit; and a control circuit that switches the communication circuit between the first data communication scheme at timing when the microwave oven does not generate the microwave and the second data communication scheme at timing when the microwave oven generates the microwave according to the recognition result of the recognition circuit.
Another document (for example, see Patent Document 2) discloses a wireless LAN system in which a plurality of terminal devices perform data communication each other near a microwave oven by using a radio wave in a frequency band near a microwave for a heating purpose generated from the microwave oven, characterized in that each of the terminal devices includes communication means for communicating in a first data communication scheme when the microwave is not generated and a second data communication scheme when the microwave is generated, and the microwave oven includes: a radio interference model pattern data storage unit for storing radio interference model pattern data corresponding to an interference radio wave generated from the microwave oven; a wireless modem unit for communicating with the terminal devices; and a control unit for controlling the radio interference model pattern data storage unit, the wireless modem unit, microwave oven functions and the like, wherein the microwave oven transmits the radio interference model pattern data corresponding to an interference radio wave to each of the terminal devices immediately before generating the microwave, and each of the wireless terminal devices that receives the data switches to the second data communication scheme that suppresses a noise of an interference radio wave for the received data to be received thereafter by using the radio interference model pattern data.
Yet another document (for example, see Patent Document 3) discloses a home network appliance that includes: an interference source that generates an electromagnetic wave wherein the electromagnetic wave is not used for communication and interferes with wireless communication; storage means for storing interference source information on the interference source; and notification means for transmitting the interference source information, wherein the home network appliance is capable of performing stable wireless communication by alleviating an influence of the interference to the communication.
Patent Document 1: Japanese Patent Laid Open Publication No. 2000-224176
Patent Document 2: Japanese Patent Laid Open Publication No. 2002-300171
Patent Document 3: Japanese Patent Laid Open Publication No. 2006-80741